1. Field of the Invention
The present invention relates to a process for producing a fluorinecontaining block copolymer, and more particularly to a process for producing a fluorine-containing block copolymer having good solvent and cold resistances.
2. Related Art
JP-B-54-1585 discloses a fluorine-containing polymer composition comprising a fluorine-containing polymer copolymerized with not more than 3% by mole of bromine-containing olefins, and an organic peroxide. Peroxide-crosslinked products from the composition show a fairly good cold resistance, but the solvent resistance is not satisfactory yet, as shown in the results of after-mentioned Comparative Example 1 (1).
JP-B-58-4728 also discloses a fluorine-containing, polysegmented polymer obtained by copolymerization reaction, using an iodine compound as a chain-transfer agent. No improvement in the cold resistance is expectable, because the iodine compound as a chain-transfer agent is a low molecular weight compound.
Thus, they cannot be used as vulcanization molding materials such as seal materials for a fuel oil system requiring good solvent and cold resistances.